Crank-case construction



Se t. 16, 1930. J. B. FISHER CRANK CASE CONSTRUCTION Filed April 20, 1927 Patented Sept. 16, 1930 UNITED STATES PATENT OFFICE JAMES FISHER, OF WAUKESHA, WISCONSIN, ASSIGNOR TO WAUKESHA MOTOR COM- PANY, OF WAUKFSI-IA, WISCONSIN, A CORPORATION OF WISCONSIN CRANK-CASE CONSTRUCTION Application filed April 20,

This invention relates to crank case construction and covers particularly an improved and more practical structure for more rigidly supporting the main crank shaft bearings and for strengthening and stiffening the crank case against flexure and distortion.

The inertia load on the main bearings in a crank case, when the engine is running causes inner stresses and strains in the crank case structure. This is particularly true in crank case construction in which the side walls drop below the shaft center and in such structure there. is a bending action in the case and a spreading and contracting tendency of the lower edges of the case. Such spreading and contraction could be. offset and prevented by a truss or chord member across the bottom such structure would be complicated and imzo practical on account of the resulting inacn: no

s cJ

cessibility.

The important object of this invention is to overcome the spreading and contracting tendency of the lower edges of the crank case by providing truss structures for supporting the main bearings for the crank shaft. Each truss structure comprises upper and lower arch members extending between the side walls of the crank case and connected by a web, the lower arch members directly supporting the bearings structure.

Another object of the invention is to provide box beam structures along the outside of the crank case side walls at the bottom thereof and to so arrange the beam structures that their walls will cooperate with the arch members to form rigid truss structures for supporting the various bearings, said beam structures serving also to stiffen and brace the crank case against flexure. and distortion.

Referring to the drawings,

Figure 1 is a plan view of a crank case with parts broken away;

Fig. 2 is a sectional view on plane 22 of Fig. 1;

Fig. 3 is a sectional view on plane 33 of Fig. 1; and

Fig. 4 is a sectional view on plane 4-4 of Fig. 2.

The crank case shown is for a 6-cylinder en- 1927. Serial No. 185,141.

gine and comprises the side walls 10 and 11 and a top wall 12, in which top wall are the openings 13 over which the cylinder structures are mounted.

For supporting the main bearing structures B for the crank shaft I provide, in accordance with my invention, the truss structures T. Each truss structure comprises the upper and lower arch members 14 and 15 extending between the side walls 10 and 11 of the crank case, the lower arch member con taining the upper bearing member I), and between the upper and lower arch members and the upper bearing extends the vertical web part 16. The entire truss structures are preferably an integral part of the crank case casting. The arch members are, as shown, of fiat rectangular cross section so that the truss structure is of I-beam cross section.

In ractice the engine crank shaft (not shown is journaled between the upper and lower members 6 and b of the bearing structures and during inertia load on the bearings the arch members 15 are subjected alternately to heavy compression and tension, the compression tending to spread the arch members and the sides of the crank case while the tension will tend to draw the arch member ends and the crank case walls toward each other, the result being that breakage and cracks may form at the weakest point which will probably be at the corners 0 at the ends of the upper bearing members 1) unless the bearing supporting arch members were sufficiently strengthened. By providing the truss arrangement described the bearing supporting arch members will be sufficiently strengthened and reinforced so that breakage or cracking will be entirely prevented. The crank shaft or bearing load will be transferred in part to the upper arch member 6 to the web 16. The weight of the crank shaft structure and bearing structures and the down thrust of the pistons will be transmitted through the arch members to the side frame sections 10 and 11 and to the frame 17 on which the crank case is mounted.

To strengthen and stiffen the crank case against bending or sagging I provide the hollow or box beam structures D along the out case;

side ofthe wall sections 10' and 11 and have preferably shaped 'thes'efbeam structures so that their upper walls 181 form a continuation of the upper arch members 14 of the truss structures. The lower walls'19 of the beam structures willthen extend betweenthe ends of the arch members and form extended :toot

or seatingsurfaces therefor besidesholding' ethe arch membersagainst spreading at their 7 ends. The-arrangement will materially stiff en and strengthen the truss structures and increase their supporting capacity and rigidity. In other words, the beam structures" D will act as, braces forresisting=longitudinal expansion and contraction of the truss 5 structures. With such strong andrigid truss structures chord members between the truss ends arefentirely' unnecessary andjthe space 3 below the bearings and truss structures can cast, integral with the. truss structures for journaling the engine cam shaft, and above the line; of; the cam shaft are provided the enclosures or chambers 22 into which extend the valvefstems "and valve tappetsf (not shown) for cooperatingwith the camshaft,

these chambers 22 being accessible through the side walls of the crank hand; holes-23 in I thus produce case structure which may be in the form of a single casting-and which is comparatively light and whichincorporates truss strum; tures for supportlng and maintaining the crank shaft in accurate alignment and for pre entlng distortlon or bending of the crank case as a whole or of its walls.

I claim as follows a 1, A crankcase structure-comprising"side walls, truss structures. between said walls structures;

case and a strong" and rigid crank forming continuations of the upper arch members of said truss structures, horizontal walls extending between' said diagonally extending walls and the lower ends of said side walls, and bearingrsupporting frames interpose'din said truss structures above the lower ends of said side walls. I {Q1 3. A crank case structure comprisingside malls and top walh truss structuresof I- beani construction-cOnnecting the side 'walls cross section'extending along the sides of the crank case; the upper walls of said beams be- "ing alignedwith andconstituting continuations of the upper elements of -the tru'ss and each arched upwardly as a whole, and hollow beams 01" approximatelytriangular .4. A crank-case structure.comprising side V walls and a top wall, truss structures of I- 5 beam construction connecting the side walls and each arched upwardly asa whole, and hollow beams of, approximately triangular crosssection extendingalong thesides of the crank case, cthe upper walls of saidbeams be ing aligned with and constituting continuations of the upperelementsof the (truss structures, the lower Wallsof the beamsbeing vsubstantially horizontal and V the lower elements of the.trussstructures terminating at the inner edgesofsaidlower walls. J

- IH'WEllQ/SS whereof, I have hereunto set my JAMES B- FIS E hand this'Z day of April; 1927. f

each comprising upper and lowerupwardly curved arch members and a web member,

the lower ends of said side walls and said extension walls. .l a 2. A; crank structure in the form ofan inte gral casting comprising side walls, sets of upper andlower upwardly arched arch members and intervening web members extendmg between said side walls to form truss structures, diagonally extending walls out-' side of said sidewalls and aligned with and crank shaft bearing structures supported on said truss structures, a wall extending outrdly fromeach oisaid'side walls and ned with and forming a continuation of the upper arch members of said truss structures, and bottom walls extending between 

